The present invention relates to a method and an apparatus for controlling the speed and spacing of a motor vehicle. A system for controlling the speed and spacing of a motor vehicle can, without intervention by the driver, control a previously set speed and/or a previously set spacing from a preceding vehicle or from objects located in the direction of travel. This is done with appropriate consideration of the surroundings of the motor vehicle and optionally of further parameters, for example weather conditions and visibility. A system of this kind is also referred to as an adaptive cruise control (ACC) system. The ACC system must be flexible enough, especially in view of today""s increasing traffic density, to react suitably to all driving situations.
German Patent No. 44 37 678 describes a method for controlling the spacing of motor vehicles based on the goal of making possible a flexible and variable definition of the reference spacing in the spacing control system. The method takes into account a desired spacing, predefined by the driver of the motor vehicle, from the preceding vehicle. The spacing control system can be activated when the desired spacing lies within a specific spacing range between a minimum and a maximum value. At the moment the spacing control system is activated, the desired spacing is set to the current spacing from the preceding vehicle. When the spacing control system is activated, the driver of the motor vehicle can increase or decrease the desired spacing by gently braking or accelerating. Preset maximum acceleration and deceleration values must not be exceeded in this context, since otherwise deactivation of the system would occur. Defined minimum and maximum threshold values cannot be exceeded in the course of changes in the desired spacing by the driver of the motor vehicle.
German Patent Application No. 195 14 023 describes a method and an apparatus for controlling the speed and spacing for a motor vehicle in which the speed is controlled as long as there is no preceding vehicle located within a predefined detection region in front of the vehicle. If a preceding vehicle is located inside the predefined detection region in front of the vehicle, the spacing from the preceding vehicle is controlled. This spacing control system establishes a reference spacing from the preceding vehicle that is speed-dependent, possesses a fixed component, and moreover can be adaptively adjusted to weather conditions, the time interval with respect to the preceding vehicle, and driver behavior. The Application is based on the goal of developing a control method for lane changes. In achieving this goal, a distinction is made as to whether a lane change is being made to the right or to the left.
In the case of a lane change to the left, which is detected by fact that the directional indicator (blinker) is set to the left, either the reference spacing from the preceding vehicle is reduced, or spacing control is terminated at the time the blinker is set. In the former case of a reduced reference spacing, the vehicle is accelerated in order to achieve the now-smaller reference spacing. Acceleration takes place to no more than the speed that was set by the driver in the spacing control Tempomat (cruise control). As soon as the directional indicator is moved back out of the xe2x80x9cleftxe2x80x9d position into the xe2x80x9cneutralxe2x80x9d or xe2x80x9crightxe2x80x9d position, the reference spacing is once again set back to the normal value. In the second case, the spacing control system is shut off and an acceleration control system is activated. In this, a minimum spacing from the preceding vehicle is defined for the system; when this is reached, the acceleration control system is shut off, and a transition is made back to spacing control.
In the case of a lane change to the right, which is detected by the fact that the directional indicator (blinker) is set to the right, if the result is that a preceding vehicle leaves the detection region, then acceleration is set to a maximum value. This maximum value is equal to the greater of the two values zero or the actual acceleration value at the time the preceding vehicle left the detection region. In graphic terms, this prevents a preceding vehicle from being overtaken on the right when a change is made to a right-hand lane. Once again, in the case of a lane change to the right, acceleration occurs to no more than the speed that was set by the driver in the spacing control Tempomat.
German Patent No. 42 00 694 describes a method for controlling the speed and spacing of a vehicle. With this method, the vehicle control system is interrupted for a predefined period of time, and the control system is then reactivated. The interruption can be accomplished by actuating the blinker (directional indicator). If the left blinker is set above a specific speed, the system then concludes that a passing maneuver is imminent. In this case the spacing control system is interrupted for a predetermined period of time so that the vehicle can be accelerated up to the maximum speed predefined by the driver. The spacing control system then re-engages. In other words, the spacing from the preceding vehicle is measured and the instantaneous speed of the vehicle is reduced, when a safety spacing is reached, until the vehicle is trailing the preceding vehicle at its speed. Re-engagement of the spacing control system is accomplished after the expiration of timing elements that can also be speed-dependent, in such a way that the so-called xe2x80x9cdriver dominancexe2x80x9d decreases from a value of 1 (100% driver dominance) to a value of 0 (100% controller dominance). If the right blinker is set or the left blinker is actuated below a minimum speed, it is assumed that merely a lane change, rather than a passing maneuver, is taking place. In this case an interruption of the spacing control system does take place for a specific time period, but the control system does not perform any acceleration. If no object is located within the measurement region, the driver dominance rises as a function of time, for example in linear fashion within two seconds, to a value of 1.
The references known from the existing art concern themselves with an imminent passing maneuver that is detected by the fact that a blinker is set. There is no information in the existing art regarding the situation in which a driver of a vehicle is already traveling in the outermost left lane of a road and would like to make the preceding vehicle aware of his or her own desire to pass.
An object of the present invention is to provide a method and an apparatus that reliably and conveniently control the ACC system in those situations in which the driver of a motor vehicle wishes to make the driver of a preceding vehicle aware of his or her own desire to pass.